QuickSync: A Quickly Synchronizing PoS-Based Blockchain Protocol

To implement a blockchain, we need a blockchain protocol for all the nodes to follow. To design a blockchain protocol, we need a block publisher selection mechanism and a chain selection rule. In Proof-of-Stake (PoS) based blockchain protocols, block publisher selection mechanism selects the node to publish the next block based on the relative stake held by the node. However, PoS protocols, such as Ouroboros v1, may face vulnerability to fully adaptive corruptions. In this paper, we propose a novel PoS-based blockchain protocol, QuickSync, to achieve security against fully adaptive corruptions while improving on performance. We propose a metric called block power, a value defined for each block, derived from the output of the verifiable random function based on the digital signature of the block publisher. With this metric, we compute chain power, the sum of block powers of all the blocks comprising the chain, for all the valid chains. These metrics are a function of the block publisher's stake to enable the PoS aspect of the protocol. The chain selection rule selects the chain with the highest chain power as the one to extend. This chain selection rule hence determines the selected block publisher of the previous block. When we use metrics to define the chain selection rule, it may lead to vulnerabilities against Sybil attacks. QuickSync uses a Sybil attack resistant function implemented using histogram matching. We prove that QuickSync satisfies common prefix, chain growth, and chain quality properties and hence it is secure. We also show that it is resilient to different types of adversarial attack strategies. Our analysis demonstrates that QuickSync performs better than Bitcoin by an order of magnitude on both transactions per second and time to finality, and better than Ouroboros v1 by a factor of three on time to finality

FNNC: Achieving Fairness through Neural Networks

In classification models fairness can be ensured by solving a constrained optimization problem. We focus on fairness constraints like Disparate Impact, Demographic Parity, and Equalized Odds, which are non-decomposable and non-convex. Researchers define convex surrogates of the constraints and then apply convex optimization frameworks to obtain fair classifiers. Surrogates serve only as an upper bound to the actual constraints, and convexifying fairness constraints might be challenging. We propose a neural network-based framework, \emph{FNNC}, to achieve fairness while maintaining high accuracy in classification. The above fairness constraints are included in the loss using Lagrangian multipliers. We prove bounds on generalization errors for the constrained losses which asymptotically go to zero. The network is optimized using two-step mini-batch stochastic gradient descent. Our experiments show that FNNC performs as good as the state of the art, if not better. The experimental evidence supplements our theoretical guarantees. In summary, we have an automated solution to achieve fairness in classification, which is easily extendable to many fairness constraints

Endoscopic early detection of premalignant changes in stomach with mucosal biopsy in patients with symptomatology of acid peptic disease

Background: Stomach cancer is the second-most common cancer among men and third-most among females in Asia and worldwide. The symptoms and sign of the stomach cancer are often reported late when the disease is already in advanced stages and 5-year survival is less than 30% in developed countries and around 20% in developing countries. Early detection of cancer stomach is still remains challenge to the gastroenterologist.Methods: This study was done to detect early premalignant changes by upper GI scopy and histopathological examinations of mucosal biopsies in patients with symptoms of acid peptic disease not responding to any type of medications. 200 patients above 20 years of age with acid peptic disease symptoms selected for upper GI scopy and histopathology with follow up from 6 months to two years to detect whether premalignant lesion changes to malignancy.Results: Different types of inflammatory lesions of gastric mucosa detected endoscopically and on histopathology in our study. In 7 patients premalignant changes were detected and 7 patients already had gross malignancies in stomach. Out of the total number of biopsies included in the study, we observed lesions of atrophic type in 4 antral biopsies (2.25%) and 3 biopsies of the gastric body (1.69%). All were grade 1 as per Sydney classification.Conclusions: Upper endoscopy with histopathology has excellent output to detect early premalignant changes in stomach mucosa, though it is long way to continue this study to correlate both

HORMONAL AND NUTRITIONAL REGULATION OF MOLTING, METAMORPHOSIS, AND REPRODUCTION IN BED BUGS, \u3cem\u3eCimex lectularius\u3c/em\u3e

The bed bug, Cimex lectularius is an obligate hematophagous ectoparasite that feeds on humans. The increase in travel and development of insecticide resistance to commercially available insecticides have enabled the bed bug population to resurge, causing economical and psychological trauma to the human population. Lack of knowledge about the basic molecular biology of bed bugs has motivated us to study the key aspects of molting, metamorphosis, and reproduction. A blood meal triggers expression of various genes that enable bed bugs to molt or undergo metamorphosis. Molting and metamorphosis in bed bugs are regulated by two key hormones: 20-hydroxyecdysone (20E) and juvenile hormone (JH). JH induces expression of Krüppel homologue 1 (Kr-h1) gene. Higher expression of Kr-h1 in the penultimate nymphal instar represses ecdysone inducible gene E93 and the development of adult characteristics in the insect. E93 is expressed during the last instar stage in the absence of Kr-h1. E93 promotes the development of adult structures and metamorphosis to the adult stage. Studies on reproduction have also shown that blood meal and mating are essential for vitellogenin gene expression and oocyte maturation in bed bugs. JH and 20E regulate reproduction in bed bugs. Detailed studies on the involvement of juvenile hormone in reproduction using the next generation sequencing technology identified genes that regulate reproduction in bed bugs. V-Maf, avian musculoaponeurotic fibrosarcoma oncogene homolog B (MafB), forkhead box protein (Foxl2) and heparanase were found to play key roles in regulation of reproduction. The role of ABC transporters was also studied using RNA interference. ABC transporters (ATP-binding cassette) are involved in active transport of various molecules including steroid hormones, cuticle lipids, and other molecules. ABC transporters were also shown to be involved regulation of reproduction, molting and metamorphosis in bed bugs. This study lays a foundation for future research aimed at the development of novel methods for controlling bed bugs

Zooming Past Motor-Voter: An Analysis of How Automatic Voter Registration Policies Impact Voter Turnout in the United States

In the 1990s, the National Voter Registration Act (NVRA) mandated that motor vehicle agencies process voter registration applications in a policy known as motor-voter. From motor- voter emerged automatic voter registration, or AVR, wherein eligible voters are registered to vote automatically from a transaction with certain state-designated agencies. In 2016, Oregon became the first state to implement an automatic voter registration policy, though a number of states have since followed. In this paper, I analyze the impact of AVR on rates of voter turnout and rates of voter registration, making this paper among the first to identify the effect of automatic voter registration on voter turnout. Using difference-in-difference models, I compare changes in turnout by age, race, and state partisan control for the states that have implemented AVR policies to changes in turnout by age, race, and state partisan control for the states that have not adopted AVR policies. I also compare changes in registration for the states that have implemented AVR policies to changes in registration for the states that have not adopted AVR policies. Using data from the 2012, 2014, 2016, and 2018 Election Administration and Voting Surveys as well as data from the 2012, 2014, 2016, and 2018 Current Population Survey’s Voting and Registration Supplements, I find AVR to have a small but positive impact on overall rates of voter registration and voter turnout. This study has implications for states pondering the adoption of automatic voter registration policies and adds to the body of literature examining the impact of electoral reforms on voter turnout